Question 3
- State two reasons for creating openings in walls.
- State two advantages of timber formwork over steel formwork.
- Explain the function of each of the following materials in relation to concrete
work:
- aggregate;
- cement;
- water;
- admixture.
Majority of the candidates were able to state the:
- reasons for creating openings in walls;
- advantages of timber formwork over steel formwork.
However, they were unable to state the function of each of the given concreting materials.
The expected response to question 3 is as given below:
- Reasons for creating opening in wall
- To provide a space for door.
- To provide a space for window.
- To meet ornamental/architectural design of building e.g. a circular hole specifically created in wall as design feature.
- To create a space for installing air conditioner or fixing bracket fans.
- To provide ventilation.
- To provide illumination or daylight effect.
- Advantages of Timber Formwork over Steel Formwork
It is:
- easily cut into any desired shape;
- readily available;
- relatively cheap;
- easily re-cycled.
- Functions of concrete materials
(i) Aggregate – This is a general term used to describe inert materials such as sand and stone which are binded together by cement paste to form a solid mass.
(ii) Cement – This is a binding material in concrete/mortar. It binds the particles of aggregate to form a solid mass.
(iii) Water – When water is added to cement, the processes of hydration and setting will follow which will later lead to hardening process. In addition, water performs the following functions:
- To damp the aggregate.
- To make the concrete workable so that it can be placed
easily and uniformly.
- It lubricates the aggregates.
(iv) Admixture is added to a concrete mix to improve or change its properties |